1. Field of the Invention
The present invention is directed to an electronic navigation device. More particularly, the present invention is directed to a handheld electronic navigation device, having combined in a single handheld housing a GPS unit, an electronic compass, and an altimeter.
2. Description of the Related Art
Handheld navigation devices are well known, widely used, and are becoming increasingly popular. For example, GPS units, which have the ability to calculate a position and display map, route, and location information are becoming increasingly popular. Conventional GPS units also have the ability to calculate a user's heading, or direction of travel, by determining the movement of a user over time. However, conventional GPS units are unable to determine heading or direction information when the user of the GPS device is not traveling at a sufficient speed, typically in the order of 4 mph or greater.
Accordingly, an outdoor enthusiast (such as a hiker or biker), being often at a standstill or traveling less than a sufficient speed, must typically carry additional instruments, such as a compass, in order to instantaneously determine direction or heading information. Furthermore, it is often additionally desired by such enthusiasts to have knowledge of altitude information. Retaining this information requires yet an additional instrument, such as an altimeter. Carrying multiple such devices is particularly cumbersome when hiking or biking.
In an attempt to overcome the foregoing, one available product combines a GPS unit and a barometric pressure sensor in the same housing. However, the pressure sensor is used only to augment GPS derived altitude information, not as a separate indicator of altitude. Another available product, the XL1000 by SILVA combines a GPS unit and an electronic compass, but not an altimeter.
Additionally, it would be desirable in a navigation unit to include extensive mapping information, and provision for uploading even additional map information as desired. Furthermore, it would be desirable for any such unit to have convenient options for calibrating the altimeter. In this regard, it is well known to calibrate an altimeter with known altitude information input by a user. It is also known, such as in a product known as the “Freestyle Altimeter Watch”, to permit storage in a memory of two known altitudes, such that when a user is in one of the two locations, the correspondingly stored altitude information may be recalled for calibrating the altimeter. While useful, this approach is limited to a pair of locations and, as with other known approaches, requires user input.
Accordingly, the need exists for an improved navigation unit. Particularly, the need exists for a portable navigation unit having GPS, compass, and altimeter outputs. The present invention fills the foregoing identified needs, and other needs, while overcoming the drawbacks of the prior art.